It is desirable to provide useful and efficient lighting to illuminate aisles both at the retail display level and warehouse storage facilities. Typically, such aisles are lighted by suspended luminaires having optical units comprised of plastic or glass. These optical units may include one or more refracting components such as refracting prisms and, in some cases, may also include a reflector. See, for example, the improved luminaire with up-light control disclosed in U.S. Pat. No. 4,858,091 which is assigned of record to Applicants' assignee, Holophane Corporation.
The above-mentioned suspended luminaires have been found in practice to be unsuitable for illuminating aisles because the vertical surfaces of the aisles are not provided with uniform lighting. More specifically, it has been found that undesirable dark spots are created on the aisles. The fixtures have also been found to produce undesirable glare to workers in the aisle.
Consequently, a need has developed for an improved optical unit for use in suspended aisle luminaires which will provide uniform lighting of the vertical surfaces of the corresponding aisles. Such an optical unit should produce light which is comfortable to view by workers or customers in the aisle and thus be devoid of undesirable glare.